Manufacture of lead



Patented Oct. 28, 1952 UNITED STATES PATENT OFFICE MANUFACTURE OF LEAD Leonard F. Taylor, South Darley, near Matlock,

and Patrick W. Wright, Holloway, near Matlock, England, assignors to H. J. Enthoven & Sons Limited, London, England, a British com- No Drawing.

Application April 17, 1950, Serial No. 156,488. In Great Britain May 11, 1948 per.

One of the tests laid down by the British Standards Institution in their British Standard Specification (B. S. S. No. 334 of 1934) for chemical lead is the so-called flash-test which depends on the peculiar behaviour of a sample of lead at a particular temperature (the flashpoint) when immersed in concentrated sulphuric acid and heated.

An investigation by us into the effect of various percentages of different impurities upon the flash-point of lead has revealed some very inter esting facts. In particular it has been ascertained that quite small amounts of some metal impurities in lead lower the flash-point considerably, this being particularly the case with antimony. For example, whereas the flash-point of a sample of lead substantially free from antimony Was 322 C., the flash-point of lead containing 0.01% of antimony was 248 0., containing 0.02% antimony was 243 0., containing 0.03% antimony 240 C., and containing 0.04% antimony 238 C.

We have found, much to our surprise, that the presence of a small amount of nickel in lead of progressively increased antimony content-which lead normally suffers from a sharp and progressive drop in flash-point as above noted-has its flash-point actually raised. For example 0.01 per cent of nickel in addition to from 0.01 to 0.02 per cent of antimony raises the flash-point to about 326 C. Similarly 0.02 per cent of nickel in addition to from 0.01 to 0.03 per cent of antimony raises the flash-point to 330 C.

The present invention, therefore, consists in partially or completely eliminating the adverse effect of antimony in lowering the flash-point of lead, or even raising the flash-point of lead, notwithstanding the presence of a small amount of antimony by incorporating therein a small amount of nickel. From the industrial standpoint the importance of being able to maintain and even raise the flash-point of lead without resorting to the expense of extreme refining is apparent, and from this point of view the invention consists in deliberately desisting from refining lead as regards antimony content beyond about 0.03 per cent and by adding a small per cent of nickel to compensate for the antimony content.

The greater the amount of nickel introduced the greater may be the amount of antimony left in the lead, as is indicated by the following table of contents and flash-points:

[Flash-points, C.]

Antimony content of lead percent. Nil 0.01 0.02 0.03 0.04 0.05 0.06

. 0.0.0.0.0.0.0. iced antimony only- 322 248 243 240 238 238 238 ea an imony 0.01% Ni: }321 326 326 319 314 311 309 i'lgggjfi fffl }s21 330 330 330 328 326 32?.

ea. an imony 092% }322 329 330 330 330 330 What we claim is:

Lead containing from 0.01 to 0.06 per cent by weight of antimony together with nickel ran ing from 0.01 to 0.03 per cent by weight, the remainder being lead, the nickel serving to obviate the adverse efiect of the antimony in lowering the flash-point of the lead.

L. F. TAYLOR. P. W. WRIGHT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,067,507 Smith Jan. 12, 1937 2,115,300 Butcher Apr. 26, 1938 FOREIGN PATENTS Number 1 Country Date 326,818 Great Britain Mar. 18, 1930 OTHER REFERENCES The Metal Industry Handbook and Directory, 11:42, page 151. Louis Cassier 00., London, Eng- 

